TITLE: GCN CIRCULAR NUMBER: 29220 SUBJECT: Swift Trigger 1015615 is not a GRB DATE: 21/01/02 00:33:05 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), M. G. Bernardini (INAF-OAB), P. D'Avanzo (INAF-OAB), C. Gronwall (PSU), J.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (PSU), N. P. M. Kuin (UCL-MSSL), S. Laha (GSFC/UMBC/CRESST), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), D. M. Palmer (LANL) and T. Sbarrato (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team: At 00:17:12 UT, the Swift Burst Alert Telescope (BAT) triggered on background noise during high background increase while entering the SAA (trigger=1015615). The BAT light curve shows the background increase near the SAA, without any significant burst structure. The XRT began observing the field at 00:18:47.7 UT, 95.1 seconds after the BAT trigger. No valid point source was found in the XRT data. Automated position reported through GCN Notices is due to a cosmic ray, and should be ignored. This event was initiated by the BAT rate increase on approach to the SAA, which yielded an image with a marginal (6.5 sigma) fluctuation. Based on the lack of a GRB-like rate increase above the ramping up BAT rates on SAA approach, the low significance of the image peak, and the non-detection of an XRT afterglow, we believe that this is not an astrophysical event.